Method of correcting gravity-induced error in quantum cryptography system, method of quantum cryptography authentification using the same, and user terminal and server

Patent metadata

Field	Value
Publication number	US-11489667-B2
Application number	US-202117141674-A
Country	US
Kind code	B2
Filing date	Jan 5, 2021
Priority date	Jul 13, 2020
Publication date	Nov 1, 2022
Grant date	Nov 1, 2022

Abstract

A method of correcting gravity-induced error in quantum cryptography system, which is capable of improving accuracy when an optical cable is not installed and photons are transmitted through an artificial satellite, is disclosed. The method performed by an electronic device, comprises receiving a distance (r) to a satellite that receives polarized photon from a sender and transmits the polarized photon to a receiver, receiving an angular momentum per unit mass of the satellite (lobs), and calculating a rotation amount of the polarized photon, which is induced by a warp of space due to gravity by using the distance to the satellite and the angular momentum per unit mass of the satellite (lobs). The rotation 2Θ of the polarized photon is calculated by the following equation,sin⁢⁢Θ⁡(r)≅-lobsrrs⁢1-rsr,wherein ‘rs’ is the Schwarzschild radius of the Earth.

First claim

What is claimed is:

1. A method of correcting gravity-induced error in quantum cryptography system, which is performed by an electronic device, the method comprising:
receiving a distance to a satellite that receives polarized photon from a sender and transmits the polarized photon to a receiver;
receiving an angular momentum per unit mass of the satellite; and
calculating a rotation amount of the polarized photon, which is induced by a warp of space due to gravity by using the distance to the satellite, a Schwarzschild radius of the Earth, and the angular momentum per unit mass of the satellite.

2. The method of claim 1 , wherein the rotation of the polarized photon is calculated by the following equation,

sin
⁢

⁢

Θ
⁡

(
r
)

≅

-

l
obs

rr
s

⁢

1
-

r
s

r

,

wherein ‘2Θ’ is rotational amount of polarized photon, ‘l obs ’ is the angular momentum per unit mass of the satellite, ‘r’ is the distance to the satellite, and ‘r s ’ is the Schwarzschild radius of the Earth.

3. A method of quantum cryptography authentication, comprising:
generating, by a server, an arbitrary bit;
selecting, by the server, a transmission filter to transmit the arbitrary bit;
transmitting, by the server, photons polarized according to the transmission filter to a satellite;
selecting, by a user terminal, a reception filter to receive the photons;
receiving, by the user terminal, a distance to the satellite and an angular momentum per unit mass of the satellite;
calculating, by the user terminal, a rotation amount of polarized photons, which is induced by warping of space due to gravity by using the distance to the satellite and the angular momentum per unit mass of the satellite;
rotating, by the user terminal, the reception filter according to of the rotation amount of the polarization;
receiving, by the user terminal, polarized photons transmitted from the satellite through the reception filter;
sharing information of the transmission filter and the reception filter, by the server and the user terminal, with each other;
generating a first secret key by the server and a second secret key by the user terminal through the shared information of the transmission filter and the reception filter;
transmitting, by the user terminal, the second secret key to the server; and
checking, by the server, whether the first secret key and the second secret key match.

4. The method of claim 3 , wherein the user terminal calculates the rotation of the polarized photon is calculated by the following equation,

sin
⁢

⁢

Θ
⁡

(
r
)

≅

-

l
obs

rr
s

⁢

1
-

r
s

r

,

wherein ‘4Θ’ is rotational amount of polarized photon, ‘l obs ’ is the angular momentum per unit mass of the satellite, ‘r’ is the distance to the satellite, and ‘r s ’ is the Schwarzschild radius of the Earth.

5. The method of claim 3 , wherein the user terminal receives the distance to the satellite and the angular momentum per unit mass of the satellite from the satellite or the server.

6. The method of claim 3 , wherein the server and the user terminal share the information of the transmission filter and the reception filter through a wired communication network or a wireless communication network.

7. The method of claim 3 , wherein the transmission filter and the reception filter are selected randomly by the server and the user terminal, respectively.

8. A server comprising:
a random bit generator for generating random bits;
a transmission filter selection unit for selecting a transmission filter for transmitting polarized photon;
a photon transmission unit converting the generated random bits into photons polarized through a selected transmission filter and transmitting the photons;
a communication unit that receives information of reception filter from a user terminal and transmits information of the transmission filter information to the user terminal;
a secret key generator for generating a first secret key using the random bits according to the information of the reception filter and the transmission filter; and
an authentication unit performing a user authentication by receiving a second secret key from the user terminal and by comparing the second secret key with the first secret key.

9. The server of claim 8 , wherein the transmission filter selection unit selects the transmission filter randomly.

10. A user terminal comprising:
a reception filter selection unit selecting a reception filter for receiving polarized photons transmitted from a server;
a reception filter correction unit correcting an angle of the reception filter;
a photon receiving unit receiving polarized photons from a satellite through the corrected reception filter;
a communication unit receiving information of a transmission filter from a server and transmitting information of the reception filter to the server; and
a secret key generator generating a second secret key by using information of polarized photons, the information of transmission filter, and the information of the reception filter; and
wherein the communication unit transmits the second secret key to the server.

11. The user terminal of claim 10 , wherein the reception filter correction unit calculates the rotation of the polarized photon is calculated by the followin

Assignees

• Univ Seoul Ind Coop Found
• First Quantum Inc

Inventors

• Ahn Do Yeol

Classifications

• G06F2221/2129

  Authenticate client device independently of the user · CPC title

• H04L9/0869

  involving random numbers or seeds · CPC title

• G06F21/31

  User authentication · CPC title

• H04L9/0852 Primary

  Quantum cryptography (transmission systems employing electromagnetic waves other than radio waves, e.g. light, infrared H04B10/00; wavelength-division multiplex systems H04J14/02; WDM arrangements H04J14/03) · CPC title

• G06F21/44 Primary

  Program or device authentication · CPC title